1. Field of the Invention
The present invention relates to a film deposition system and a method of fabricating a semiconductor device employing the film deposition system, and more particularly, it relates to a chemical vapor deposition (CVD) system forming an oxide film on a semiconductor substrate and a method of fabricating a semiconductor device employing this system.
2. Description of the Background Art
In general, Japanese Patent Laying-Open Nos. 8-213379 (1996), 62-44574 (1987) and 9-275077 (1997), for example, disclose film deposition systems.
A semiconductor device formed on a semiconductor substrate has recently been refined, followed by refinement of elements such as gate electrodes forming the semiconductor device. In the process of such refinement, the interval between the gate electrodes is also narrowed. When an oxide film, for example, is formed on such gate electrodes formed at a narrow interval, voids do not disappear but remain in the oxide film even if the oxide film is heat-treated. When chemical mechanical polishing (CMP) is performed in this state for flattening the oxide film, grooves resulting from the voids are formed in the oxide film. These grooves result in short-circuit of wires or a failure in pattern formation in a later step. In order to avoid this problem, flowability with respect to heat treatment can be improved by increasing the concentration of boron or phosphorus contained in the oxide film. In this case, however, the oxide film is disadvantageously unstabilized to result in a deposit or cracking. While flowability can also be improved by increasing the time for the heat treatment, high-temperature long-term heat treatment exerts bad influence on the refined device.
While a conventional wafer of 200 mm in diameter has recently been replaced with a wafer of 300 mm in diameter, the peripheral or central portion of such a large-diametral wafer may be separated from the surface of a heater due to warping of the wafer. This results in temperature reduction in the portion separated from the heater, to damage in-plane uniformity of the film thickness and impurity concentration. In order to overcome this problem, the heater may be provided with a vacuum suction mechanism or an electrostatic suction mechanism for bringing the bent wafer into close contact with the heater. However, it is difficult to implement this as to the heater used under a high temperature of at least 400° C. in view of restriction in material. Thus, it is generally difficult to form an interlayer dielectric film on gates due to the large diameter and refinement of the device.